Semiconductor device including fin-fet

ABSTRACT

A semiconductor device including a fin field effect transistor (fin-FET) includes active fins disposed on a substrate, isolation layers on both sides of the active fins, a gate structure formed to cross the active fins and the isolation layers, source/drain regions on the active fins on sidewalls of the gate structure, a first interlayer insulating layer on the isolation layers in contact with portions of the sidewalls of the gate structure and portions of surfaces of the source/drain regions, an etch stop layer configured to overlap the first interlayer insulating layer, the sidewalls of the gate structure, and the source/drain regions, and contact plugs formed to pass through the etch stop layer to contact the source/drain regions. The source/drain regions have main growth portions in contact with upper surfaces of the active fins.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This U.S. Non-provisional application claims priority under 35 USC § 119 to Korean Patent Application No. 10-2018-0070820, filed on Jun. 20, 2018, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

Devices and methods relate to a semiconductor device including a fin field effect transistor (fin-FET) and a method of manufacturing the same.

According to the demand of high integration of semiconductor devices, it is becoming more difficult to form a plurality of contact plugs in a restricted space. Contact plugs function to provide an electrical connection between lower patterns and upper lines.

When the lower patterns are excessively recessed in a process of forming contact plugs, parasitic capacitance is generated between a gate electrode and the contact plugs, and thus, a current delay may occur.

SUMMARY

The example embodiments of the inventive concept are directed to providing a semiconductor device in which generation of parasitic capacitance is reduced and which has improved operating characteristics.

According to example embodiments, there is provided a semiconductor device including active fins extending in a first direction on a substrate, isolation layers on sides of the active fins, a gate structure formed to cross the active fins and the isolation layers and extending in a second direction that is perpendicular to the first direction, source/drain regions on the active fins on sidewalls of the gate structure, a first interlayer insulating layer on the isolation layers and formed in contact with first portions of the sidewalls of the gate structure and a first surface of the source/drain regions, an etch stop layer on the first interlayer insulating layer, a second portion of the sidewalls of the gate structure, and a second surface of the source/drain regions, and contact plugs formed to pass through the etch stop layer to be in contact with the source/drain regions, wherein the source/drain regions have main growth portions in contact with the upper surfaces of the active fins and merged growth portions in which edges of the main growth portions are merged into each other.

According to example embodiments, there is provided a semiconductor device including: active fins extending in a first direction on a substrate, isolation layers on both sides of the active fins, a gate structure formed to cross the active fins and the isolation layers and extend in a second direction that is perpendicular to the first direction, source/drain regions on the active fin at both sides of the gate structure, etch stop layers on sidewalls of the gate structure and the source/drain regions and have a sigma (Σ) shape, a first interlayer insulating layer interposed between the etch stop layers, and contact plugs formed to pass through the etch stop layer and contacting the source/drain regions.

According to example embodiments, there is provided a semiconductor device including: active fins to extend in a first direction on a substrate, isolation layers on both sides of the active fins, a gate structure formed to cross the active fins and the isolation layers and extending in a second direction, source/drain regions on the active fins on sidewalls of the gate structure, a lower etch stop layer configured to cover the isolation layers, the source/drain regions, and the sidewalls of the gate structure, a first interlayer insulating layer on the lower etch stop layer and having a height less than that of an upper end of the source/drain regions, an upper etch stop layer on a portion of the lower etch stop layer and the first interlayer insulating layer, and contact plugs formed to pass through the lower etch stop layer and the upper etch stop layer and contacting an upper surface of the source/drain regions, wherein a center line of a first one of the contact plugs is misaligned with a center line of the source/drain region in the second direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings.

FIG. 1 is a schematic layout illustrating a semiconductor device according to example embodiments of the present inventive concept.

FIG. 2 is a perspective view illustrating the semiconductor device according to example embodiments of the present inventive concept.

FIG. 3A is a cross-sectional view taken along line A-A′ of FIG. 2 according to example embodiments of the present inventive concept.

FIG. 3B is a cross-sectional view taken along line B-B′ of FIG. 2 according to example embodiments of the present inventive concept.

FIG. 3C is a cross-sectional view taken along line C-C′ of FIG. 2 according to example embodiments of the present inventive concept.

FIG. 4 is a cross-sectional view taken along line B-B′ according to example embodiments of FIG. 2.

FIG. 5 is a perspective view illustrating a semiconductor device according to example embodiments of the present inventive concept.

FIG. 6A is a cross-sectional view taken along line A-A′ of FIG. 5 according to example embodiments of the present inventive concept.

FIG. 6B is a cross-sectional view taken along line B-B′ of FIG. 5 according to example embodiments of the present inventive concept.

FIG. 7 is a perspective view illustrating a semiconductor device according to example embodiments of the present inventive concept.

FIG. 8A is a cross-sectional view taken along line A-A′ of FIG. 7 according to example embodiments of the present inventive concept.

FIG. 8B is a cross-sectional view taken along line B-B′ of FIG. 7 according to example embodiments of the present inventive concept.

FIG. 9 is a perspective view illustrating a semiconductor device according to example embodiments of the present inventive concept.

FIG. 10 is a cross-sectional view taken along line A-A′ of FIG. 10 according to example embodiments of the present inventive concept.

FIGS. 11 to 24 are views illustrating a method of manufacturing a semiconductor device according to example embodiments of the present inventive concept.

FIGS. 25 to 30 are views illustrating a method of manufacturing a semiconductor device according to example embodiments of the present inventive concept.

DETAILED DESCRIPTION

It is noted that aspects of the inventive concept described with respect to one embodiment, may be incorporated in a different embodiment although not specifically described relative thereto. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination. These and other objects and/or aspects of the present inventive concept are explained in detail in the specification set forth below. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

FIG. 1 is a schematic layout illustrating a semiconductor device according to some embodiments of the inventive concept. FIG. 2 is a perspective view illustrating the semiconductor device according to some embodiments of the incentive concept. FIG. 3A is a cross-sectional view taken along line A-A′ of FIG. 2. FIG. 3B is a cross-sectional view taken along line B-B′ of FIG. 2. FIG. 3C is a cross-sectional view taken along line C-C′ of FIG. 2. FIG. 4 is a cross-sectional view taken along line B-B′ according to some embodiments of FIG. 2. For convenience of description, only major elements are illustrated in FIG. 1, and a second interlayer insulating layer and upper contact plugs will be omitted in FIG. 2.

Referring to FIGS. 1 to 4, a semiconductor device 100 may include a substrate 101, active fins 105, an isolation layer 107, source/drain regions 110, a gate structure 140, a first interlayer insulating layer 153, an etch stop layer 160, the second interlayer insulating layer 155, contact plugs 180, and the upper contact plugs 190. The semiconductor device 100 according to some embodiments of the inventive concept may be a transistor such as a fin field effect transistor (fin-FET) in which the active fins 105 have a fin structure. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, elements should not be limited by these terms; rather, these terms are only used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the scope of the present inventive concepts.

The substrate 101 may have an upper surface extending in an X direction (first direction) and a Y direction (second direction). The substrate 101 may include a semiconductor material, for example, a IV group semiconductor, a III-V group compound semiconductor, or a II-VI group oxide semiconductor. For example, the IV group semiconductor may include silicon, germanium, or silicon germanium. The substrate 101 may include a bulk wafer, an epitaxial layer, a silicon-on-insulator (SOI) layer, a semiconductor-on-insulator (SeOI) layer, or the like.

The active fins 105 may be formed in a fin structure protruding from a main surface of the substrate 101. The active fins 105 may be disposed to extend in the Y direction (second direction). The active fins 105 may be formed from a portion of the substrate 101 or may include an epitaxial layer grown from the substrate 101. However, the active fins 105 on the substrate 101 may be recessed and the source/drain regions 110 may be disposed on side surfaces of the gate structure 140. Herein, the active fin 105 may include an element in which a channel is formed in a field effect transistor. Although not shown in the drawings, the active fin 105 may be formed of a plurality of vertically stacked semiconductor patterns. For example, each of the plurality of semiconductor patterns may extend in the Y direction, and may be disposed apart from the upper surface of the substrate 101 on the substrate 101 in the Z direction. The plurality of semiconductor patterns may be disposed apart from each other in the Z direction. Top, bottom and side surfaces of the plurality of semiconductor patterns may be surrounded by the gate structure 140.

The isolation layer 107 may define the active fins 105 on the substrate 101. The isolation layer 107 may be disposed on both sides of the active fins 105 on the substrate 101. The isolation layer 107 may be made of an insulating material. For example, the isolation layer 107 may be formed through a shallow trench isolation (STI) process. The isolation layer 107 may include, for example, one selected from an oxide, a nitride, and/or a combination thereof.

The source/drain regions 110 may be disposed on one or more of the active fins the active fins 105 on both sides of the gate structure 140. The source/drain regions 110 may be provided as a source region or a drain region of the semiconductor device 100. In some embodiments, the source/drain regions 110 may have an elevated source/drain shape of which an upper surface is disposed at a higher level than a lower surface of the gate structure 140, but the inventive concept is not limited thereto. In some embodiments of the inventive concept, the source/drain regions 110 are illustrated as having a pentagonal shape. However, the source/drain regions 110 may have various shapes, for example, any one of a polygonal shape, a circular shape, and/or a rectangular shape.

The source/drain regions 110 may be configured to be connected or merged into each other on the active fins 105. In some embodiments of the inventive concept, the source/drain regions 110 are illustrated as being configured to be connected to each other on three active fins 105, but the inventive concept is not limited thereto. For example, the source/drain regions 110 may be configured to be connected to each other on two active fins 105. In some embodiments, as shown in FIG. 4, the source/drain region 110 may be formed on one active fin 105. The source/drain regions 110 may include, for example, silicon (Si) or silicon germanium (SiGe).

The source/drain regions 110 may have a main growth portion GE and a merged growth portion ME. The main growth portion GE may be a portion which is crystal-grown from a recessed region of each of the active fins 105. The merged growth portion ME may be a portion in which edges of the main growth portions GE are merged into each other. While a crystallization process proceeds, adjacent edges of the main growth portions GE may be merged and the merged portion may vertically extend to form the merged growth portion ME.

The source/drain regions 110 may have a lateral protrusion P and a lateral protrusion end E. The lateral protrusion P may be a portion which protrudes from the source/drain region 110 in an outward direction of the active fins 105. For example, the lateral protrusion end E may be a point at which a horizontal distance between the lateral protrusion P and the active fin 105 is maximized. The lateral protrusion P and the lateral protrusion end E may be formed on both sides of the source/drain regions 110.

The source/drain regions 110 may have a first surface SUR1 and a second surface SUR2. The first surface SUR1 may be located on a lower portion of the source/drain regions 110 with respect to the lateral protrusion end E and may be formed to be inclined with respect to an upper surface of the substrate 101. The first surface SUR1 may extend from a lower surface of the source/drain regions 110 in an outward and upward direction of the source/drain regions 110. The second surface SUR2 may be located on an upper portion of the source/drain regions 110 with respect to the lateral protrusion end E. The second surface SUR2 may be uneven. The second surface SUR2 may have a wave shape. The second surface SUR2 may be in contact with the first surface SUR1 to form the lateral protrusion end E. An upper end MT of the merged growth portion ME may be located on the second surface SUR2. For example, a lowermost end of a valley region of the second surface SUR2, which is disposed between the active fins 105, may correspond to the upper end MT of the merged growth portion ME.

The gate structure 140 may be disposed to cross the active fins 105 on upper portions of the active fins 105. The gate structure 140 may include a gate insulating layer 142, a first gate electrode 145, a second gate electrode 147, a gate capping layer 148, and spacers 149.

The gate insulating layer 142 may be disposed between the active fins 105 and the first and second gate electrodes 145 and 147. The gate insulating layer 142 may include an oxide, a nitride, or a high-k dielectric material. The high-k dielectric material may mean a dielectric material having a dielectric constant higher than that of a silicon oxide film (SiO₂). The high-k dielectric material may be, for example, any one selected from aluminum oxide (Al₂O₃), tantalum oxide (Ta₂O₃), titanium oxide (TiO₂), yttrium oxide (Y₂O₃), zirconium oxide (ZrO₂), zirconium silicon oxide (ZrSi_(x)O_(y)), hafnium oxide (HfO₂), hafnium silicon oxide (HfSi_(x)O_(y)), lanthanum oxide (La₂O₃), lanthanum aluminum oxide (LaAl_(x)O_(y)), lanthanum hafnium oxide (LaHf_(x)O_(y)), hafnium aluminum oxide (HfAl_(x)O_(y)), and/or praseodymium oxide (Pr₂O₃). In some embodiments, the gate insulating layer 142 may be formed only on lower surfaces of the first and second gate electrodes 145 and 147.

The first gate electrode 145 and the second gate electrode 147 may be sequentially disposed on the gate insulating layer 142. When the semiconductor device 100 is a transistor, a channel region may be formed in the active fins 105 which cross the first and second gate electrodes 145 and 147. The first and second gate electrodes 145 and 147 may be made of different materials. The first gate electrode 145 may include, for example, a metal nitride film such as a titanium nitride (TiN) film, a tantalum nitride (TaN) film, or a tungsten nitride (WN) film. The second gate electrode 147 may include, for example, a metal material such as aluminum (Al), tungsten (W), or molybdenum (Mo), or a semiconductor material such as doped polysilicon. The first gate electrode 145 may function as a diffusion break layer with respect to the second gate electrode 147, but the inventive concept is not limited thereto. In some embodiments, the gate structure 140 may include a gate electrode including a single layer, or may include gate electrodes including three or more layers.

The gate capping layer 148 may be disposed on the gate insulating layer 142, the first gate electrode 145, and the second gate electrode 147. An upper surface of the gate capping layer 148 may be substantially coplanar with an upper surface of the spacer 119. For example, the gate capping layer 148 may include at least one of a silicon nitride film and a silicon oxynitride film, but the inventive concept is not limited thereto. In addition, in some embodiments, the gate capping layer 148 will be omitted as needed.

The spacers 149 may be disposed on both sides of the gate capping layer 148, the first gate electrode 145, and the second gate electrode 147. The spacers 149 may be disposed in contact with sidewalls of the gate insulating layer 142. The spacers 149 may insulate the source/drain regions 110 and the first and second gate electrodes 145 and 147. The spacers 149 may be made of at least one selected from an oxide, a nitride, and an oxynitride, and may be composed of a multi-layered film.

The first interlayer insulating layer 153 may be disposed on the isolation layer 107 and may be in contact with portions of surfaces of the source/drain region 110 and portions of sidewalls of the gate structure 140. The first interlayer insulating layer 153 may be in contact with the first surface SUR1 and a portion of the second surface SUR2 of the source/drain regions 110. A height of the first interlayer insulating layer 153 may be less than that of the source/drain regions 110. The height of the first interlayer insulating layer 153 may be greater than that of a corner E of the source/drain regions 110 and be less than that of the upper end MT of the merged growth portion ME. The first interlayer insulating layer 153 may be made of an insulating material and may include at least one of an oxide layer, a nitride layer, and/or an oxynitride layer. For example, the first interlayer insulating layer 153 may be a tonen silazene (TOSZ) film or a tetraethylortho silicate (TESO) film.

The etch stop layer 160 may cover an upper surface of the first interlayer insulating layer 153, the surfaces of the source/drain regions 110 except for regions in which the contact plugs 180 are disposed, and side surfaces of the gate structure 140. The etch stop layer 160 may be used to detect an etch endpoint in a process of etching a portion of the first interlayer insulating layer 153 so as to form the contact plugs 180. For example, the etch stop layer 160 may be made of silicon nitride (Si₃N₄).

The etch stop layer 160 may have a flat lower surface SUR_L in contact with the upper surface of the first interlayer insulating layer 153 and a wave-shaped lower surface in contact with an upper surface of the source/drain regions 110. In some embodiments, the flat lower surface SUR_L may be disposed at a level higher than a level LV1 of the corner E of the source/drain regions 110. In addition, the flat lower surface SUR_L may be disposed at a level lower than a level LV2 of the upper end MT of the merged growth portion ME of the source/drain regions 110. In some embodiments, the flat lower surface SUR_L may be disposed at a level which matches or is higher than a midpoint between the level LV1 of the corner E of the source/drain regions 110 and the level LV2 of the upper end MT of the merged growth portion ME, and matches or is lower than the level LV2 of the upper end MT of the merged growth portion ME.

The second interlayer insulating layer 155 may cover the etch stop layer 160. The second interlayer insulating layer 155 may be made of the same material as the first interlayer insulating layer 153, but the inventive concept is not limited thereto.

The contact plugs 180 may pass through the first interlayer insulating layer 153, the etch stop layer 160, and the second interlayer insulating layer 155 and may be disposed on the source/drain regions 110. The contact plugs 180 may electrically connect the source/drain regions 110 and the upper contact plugs 190. For example, the contact plugs 180 may have an elongated shape when viewed from above.

In some embodiments, the contact plugs 180 may be disposed such that a center line CM thereof is misaligned with a center line SDM of the source/drain region 110 on the X axis. The center line CM of the contact plugs 180 may be a line passing perpendicularly through a center point of the contact plugs 180 on an X-Y plane. The center line CDM of the source/drain regions 110 may be a line passing perpendicularly through a center point of the source/drain regions 110 on the X-Y plane. The contact plugs 180 may have a shape extending in an extension direction of the gate structure 140, i.e., the X direction (first direction) and may have a shape such as a rectangular shape or an oval shape.

In some embodiments, one end of the contact plug 180 disposed near one sidewall of the gate structure 140 may extend outward from one end of the source/drain region 110 by a first length L1, and the other end thereof may be disposed on the source/drain regions 110. One end of the contact plug 180 disposed near the other sidewall of the gate structure 140 may be disposed on the source/drain regions 110, and the other end thereof may extend outward from the other end of the source/drain region 110 by a second length L2. However, the inventive concept is not limited thereto, and the contact plugs 180 disposed on both sides of the gate structure 140 may extend in the same direction according to an arrangement of the upper contact plugs 190. The first and second lengths L1 and L2 may be variously changed. The first length L1 and the second length L2 may be determined such that the contact plugs 180 are connected to the upper contact plugs 190 each disposed on one side of each of the source/drain regions 110. In FIG. 1, the contact plugs 180 are disposed on both sides of the gate structure 140, but the inventive concept is not limited thereto. The contact plugs 180 may be disposed only on one side of the gate structure 140.

A lower surface of the contact plugs 180 may be uneven along a shape of the upper surface of the source/drain regions 110. That is, the contact plugs 180 may have a wave-shaped lower surface. Since the contact plugs 180 have the uneven lower surface, a contact area with the source/drain regions 110 may be increased.

The contact plugs 180 may include a silicide layer 181, a barrier layer 182, and a conductive layer 184. The silicide layer 181 may be disposed between the source/drain region 110 and the barrier and conductive layers 182 and 184. The silicide layer 181 may be a layer formed by siliciding the source/drain regions 110 in contact with the contact plug 180, and may be omitted in some embodiments. For example, the silicide layer 181 may have a composition represented by MSi_(x)D_(y). Here, M may be a metal, and D may be an element of a component different from M and Si. M may be one selected from Ti, Co, Ni, Ta, Pt, and/or combinations thereof, and D may be one selected from Ge, C, Ar, Kr, Xe, and/or combinations thereof.

The barrier layer 182 may function as a diffusion break layer with respect to a metal material constituting the conductive layer 184. The barrier layer 182 may be formed along upper portions of the source/drain regions 110 and sidewalls of the contact plugs 180. The barrier layer 182 may be a conductive metal nitride film. For example, the barrier layer 182 may be made of one selected from TiN, TaN, AlN, WN, and/or combinations thereof. The conductive layer 184 may be formed on the barrier layer 182. The conductive layer 184 may include a conductive material such as Al, Cu, W, and/or Mo.

In some embodiments, the upper contact plug 190 may be an interconnection line. When the upper contact plug 190 is the interconnection line, a metal via may be formed between the contact plug 180 and the interconnection line.

FIG. 5 is a perspective view illustrating a semiconductor device according to some embodiments of the inventive concept. FIG. 6A is a cross-sectional view taken along line A-A′ of FIG. 5. FIG. 6B is a cross-sectional view taken along line B-B′ of FIG. 5. For convenience of description, a second interlayer insulating layer and upper contact plugs will be omitted in FIG. 5. Since the semiconductor device of FIGS. 5, 6A, and 6B is similar to the semiconductor device described with reference to FIGS. 1 to 4 except for an etch stop layer, descriptions thereof will be provided based on differences from the above-described contents. Hereinafter, it will be understood that like numbers refer to like elements.

Referring to FIGS. 5, 6A, and 6B, a semiconductor device 100 a, according to some embodiments, may further include a protective layer 151. The protective layer 151 may cover an upper surface of an isolation layer 107, surfaces of source/drain regions 110 except for regions in which contact plugs 180 are disposed, and side surfaces of a gate structure 140. The protective layer 151 may be disposed under a first interlayer insulating layer 153 and the etch stop layer 160. For example, the protective layer 151 may be made of an oxide, but the inventive concept is not limited thereto. The protective layer 151 may protect the source/drain regions 110 from being doped with impurities. The protective layer 151 may protect the source/drain regions 110 from being recessed in a process of etching the first interlayer insulating layer 153, the second interlayer insulating layer 155, and the etch stop layer 160 so as to form the contact plugs 180.

FIG. 7 is a perspective view illustrating a semiconductor device according to some embodiments of the inventive concept. FIG. 8A is a cross-sectional view taken along line A-A′ of FIG. 7. FIG. 8B is a cross-sectional view taken along line B-B′ of FIG. 7. For convenience of description, a second interlayer insulating layer and upper contact plugs will be omitted in FIG. 7. Since the semiconductor device of FIGS. 7, 8A, and 8B is similar to the semiconductor device described with reference to FIGS. 1 to 4 except for an etch stop layer, descriptions thereof will be provided based on differences from the above-described contents. Hereinafter, it will be understood that like numbers refer to like elements.

Referring to FIGS. 7, 8A, and 8B, a semiconductor device 100 b may include the etch stop layer 160 and a first interlayer insulating layer 153. The etch stop layer 160 may cover an isolation layer 107, source/drain regions 110, and side surfaces of a gate structure 140. The etch stop layer 160 may have a sigma (Σ)-shaped cross section at both sides of the source/drain regions 110.

The etch stop layer 160 may include a lower etch stop layer 161 and an upper etch stop layer 163. The lower etch stop layer 161 may cover the isolation layer 107, the source/drain regions 110 except for regions in which contact plugs 180 are disposed, and the side surfaces of the gate structure 140. The lower etch stop layer 161 may have a lower upper surface SUR_U, a first side surface SID_1, and a second side surface SID_2. A first corner E1 may be formed between the lower upper surface SUR_U and the first side surface SID_1. A second corner E2 may be formed between the first side surface SID_1 and the second side surface SID_2. For example, the second corner E2 may be disposed at a level matching a level of a corner E of the source/drain regions 110. A third corner E3 may be formed between the second side surface SID_2 and a flat lower surface SUR_L of the upper etch stop layer 163, which is in contact with an upper surface of the first interlayer insulating layer 153.

The upper etch stop layer 163 may cover the lower etch stop layer 161 and the first interlayer insulating layer 153. The upper etch stop layer 163 may be formed in contact with a portion of the lower etch stop layer 161. The upper etch stop layer 163 may be in contact with a portion of the lower etch stop layer 161 which is disposed at a higher level than the third corner E3. The etch stop layer 160 may include the upper etch stop layer 163 and the lower etch stop layer 161 at a higher level than the third corner E3. The etch stop layer 160 may include the lower etch stop layer 161 at a lower level than the third corner E3. A portion of the etch stop layer 160 disposed at a higher level than the third corner E3 may be thicker than a portion thereof disposed at a lower level that the third corner E3.

In some embodiments, the flat lower surface SUR_L of the upper etch stop layer 163 may be disposed at a higher level than the corner E of the source/drain regions 110. The flat lower surface SUR_L of the upper etch stop layer 163 may be disposed at a level higher than a level LV1′ of the second corner E2. In addition, the flat lower surface SUR_L of the upper etch stop layer 163 may be disposed at a level lower than a level LV2 of an upper end MT of a merged growth portion ME of the source/drain regions 110. In some embodiments, the flat lower surface SUR_L of the upper etch stop layer 163 may be disposed at a level which matches or is higher than a midpoint LV12′ between the LV1′ of the second corner E2 and the level LV2 of the upper end MT of the merged growth portion ME.

A sigma (Σ) shape may be formed by connecting the lower upper surface SUR_U, the first corner E1, the first side surface SID_1, the second corner E2, the second side surface SID_2, and the third corner E3 of the lower etch stop layer 16, and the flat lower surface SUR_L of the upper etch stop layer 163.

The first interlayer insulating layer 153 may be interposed between the lower etch stop layer 161 and the upper etch stop layer 163 on both sides of the source/drain regions 110. The first interlayer insulating layer 153 may cover a portion of the lower etch stop layer 161 on both sides of the source/drain regions 110. The first interlayer insulating layer 153 may be formed in contact with the first side surface SID_1 and the second side surface SID_2 of the lower etch stop layer 161. The first interlayer insulating layer 153 may have a sigma (Σ)-shaped surface along a surface shape of the etch stop layer 160.

FIG. 9 is a perspective view illustrating a semiconductor device according to some embodiments of the inventive concept. FIG. 10 is a cross-sectional view taken along line A-A′ of FIG. 10. Since the semiconductor device of FIGS. 9 and 10 is similar to the semiconductor device described with reference to FIGS. 7, 8A, and 8B except for a protective layer, descriptions thereof will be provided based on differences from the above-described contents. In various embodiments described herein, it will be understood that like numbers refer to like elements.

Referring to FIGS. 9 and 10, a semiconductor device 100 c may further include a protective layer 151. The protective layer 151 may be disposed on a lower portion of a lower etch stop layer 161. The protective layer 151 may cover an upper surface of an isolation layer 107, surfaces of source/drain regions 110 except for regions in which contact plugs 180 are disposed, and side surfaces of a gate structure 140. For example, the protective layer 151 may be made of an oxide, but the inventive concept is not limited thereto. The protective layer 151 may protect the source/drain regions 110 from being doped with impurities. The protective layer 151 may protect the source/drain regions 110 from being recessed in a process of etching a first interlayer insulating layer 153, a second interlayer insulating layer 155, and an etch stop layer 160 so as to form the contact plugs 180.

FIGS. 11 to 24 are views illustrating a method of manufacturing a semiconductor device according to some embodiments of the inventive concept. Like numbers refer to like elements in FIGS. 1 to 30. For the sake of brief description, descriptions of contents substantially the same as those described with reference to FIGS. 1 to 10 will be omitted.

Referring to FIG. 11, trenches TI defining active fins 105 may be formed by patterning a substrate 101. Pad oxide patterns 122 and mask patterns 124 may be formed on the substrate 101. The pad oxide patterns 122 may be a layer for protecting upper surfaces of the active fins 105 and may be omitted in some embodiments. The mask patterns 124 may be a mask layer for patterning the substrate 101 and may include silicon nitride, a carbon-containing material, or the like. The mask patterns 124 may have a multi-layered structure.

The trenches TI may be formed by anisotropically etching the substrate 101 by using the pad oxide patterns 122 and the mask patterns 124. Since the trenches TI have a high aspect ratio, a width thereof may be gradually decreased toward a lower portion thereof. The active fins 105 may have a shape of which a width is gradually decreased toward an upper portion thereof.

Referring to FIG. 12, an isolation layer 107 may be formed to fill the trenches TI. The isolation layer 107 may be made of an insulating material. After the isolation layer 107 fills the trenches TI, a planarization process may be performed. During the planarization process, at least a portion of each of the pad oxide patterns 122 and the mask patterns 124 may be removed. In some embodiments, after a relatively thin liner layer is precedently formed in the trenches TI, the trenches TI may be filled with the isolation layer 107.

The isolation layer 107 filling the trenches TI may be partially removed, and the active fins 105 may protrude from the substrate 101. The isolation layer 107 may be removed, for example, through a wet etching process using at least a portion of the pad oxide patterns 122 as an etching mask. The active fins 105 may protrude upward by a certain height H1, and the protrusion height H1 may be variously changed. The pad oxide patterns 122 may also be removed during etching.

Referring to FIG. 13, a dummy gate insulating layer 132, a dummy gate electrode 135, and spacers 149 may be formed to extend and cross the active fins 105. For example, the dummy gate insulating layer 132 and the dummy gate electrode 135 may be formed through an etching process using a mask pattern layer 136.

The dummy gate insulating layer 132 and the dummy gate electrode 135 may be formed in regions in which a gate insulating layer 142 and first and second gate electrodes 145 and 147 (see FIG. 2) are to be formed. The dummy gate insulating layer 132 and the dummy gate electrode 135 may be removed during a subsequent process. For example, the dummy gate insulating layer 132 may include silicon oxide, and the dummy gate electrode 135 may include polysilicon.

The spacers 149 may be formed by forming a film having a uniform thickness on upper portions of the dummy gate insulating layer 132, the dummy gate electrode 135, and the mask pattern layer 136 and anisotropically etching the film. The spacers 149 may have a structure in which a plurality of films are stacked.

Referring to FIG. 14, the active fins 105 on both sides of the spacers 149 may be selectively removed. Recesses may be formed on both sides of the spacers 149 by removing the active fins 105. The recesses may be formed by partially etching the active fins 105 by using a separately formed mask layer (not shown) or the mask pattern layer and spacers 136 and 149 as an etching mask. For example, the recesses may be formed by sequentially performing a dry etching process and a wet etching process. Selectively, after the recesses are formed, surfaces of the recessed active fins 105 may be cured through a separate process. In some embodiments, an upper surface of the recessed active fins 105 is illustrated as being disposed at the same level as an upper surface of the isolation layer 107, but the inventive concept is not limited thereto. In some embodiments, the upper surface of the recessed active fins 105 may be disposed at a higher or lower level than the upper surface of the isolation layer 107.

Before or after the recesses are formed, a process of implanting impurities into the active fins 105 on both sides of the dummy gate electrode 135 may be performed. The process of implanting the impurities may be performed using the mask pattern layer 136 and the spacers 149 as a mask.

Referring to FIG. 15, source/drain regions 110 may be formed on the recessed active fins 105 on both sides of the spacers 149. For example, the source/drain regions 110 may be formed using a selective epitaxial growth (SEG) process. A merged growth portion ME may be formed while the source/drain regions 110 formed on the active fins 105 are connected to each other during growth thereof.

The source/drain regions 110 formed on the active fins 105 may include the same germanium (Ge) concentration or different Ge concentrations. The source/drain regions 110 may grow along a crystallographically stable surface during growth thereof and may have a pentagonal or hexagonal cross section along a Y-Z plane. However, the size and shape of the source/drain regions 110 are not limited to those shown in the drawings.

The source/drain regions 110 may include impurities. The impurities may be included in situ during growth of the source/drain regions 110, or may be included by separately implanting ions after the growth. The grown source/drain regions 110 may be provided as a source region or a drain region of the semiconductor device.

Referring to FIG. 16, a protective layer 151 may be formed to cover an upper surface of the mask pattern layer 136, side surfaces of the spacers 149, surfaces of the source/drain regions 110, and an upper surface of the isolation layer 107. For example, the protective layer 151 may be made of an oxide, but the inventive concept is not limited thereto. The protective layer 151 may protect the source/drain regions 110 from being doped with impurities. In addition, the protective layer 151 may protect the source/drain regions 110 from being recessed in a process of etching a first interlayer insulating layer 153, a second interlayer insulating layer 155, and an etch stop layer 160 (see FIGS. 5 and 9) so as to form contact plugs 180. In some embodiments, the protective layer 151 may be omitted.

A lower etch stop layer 161 may be formed on the protective layer 151. The lower etch stop layer 161 may completely cover an upper surface of the protective layer 151. For example, the lower etch stop layer 161 may be deposited through chemical vapor deposition (CVD) or atomic layer deposition (ALD).

Referring to FIG. 17, the first interlayer insulating layer 153 may be formed on the lower etch stop layer 161. The first interlayer insulating layer 153 may be formed by forming an insulating material layer covering the lower etch stop layer 161 and performing a planarization process of exposing an upper surface of the dummy gate electrode 135. The protective layer 151, the lower etch stop layer 161, and the mask pattern layer 136 on the dummy gate electrode 135 may be removed during the planarization process to expose the upper surface of the dummy gate electrode 135. Alternatively, the mask pattern layer 136 may be removed in a subsequent planarization process of a second interlayer insulating layer 155.

Referring to FIGS. 18 and 19, a portion of the first interlayer insulating layer 153 may be removed. The first interlayer insulating layer 153 may be selectively removed with respect to the dummy gate electrode 135, the spacers 149, and the lower etch stop layer 161 to expose portions of the spacers 149 and a portion of the lower etch stop layer 161. The first interlayer insulating layer 153 may be partially removed such that an upper surface thereof has a level which matches or is lower than an upper end MT of the merged growth portion ME of the source/drain regions 110 and is higher than a corner E of the source/drain regions 110.

An upper etch stop layer 163 may be formed to cover exposed upper portions of the spacers 149, an exposed upper portion of the lower etch stop layer 161, and the upper surface of the first interlayer insulating layer 153. The upper etch stop layer 163 may be formed in the same manner as in the lower etch stop layer 161.

Referring to FIG. 20, the second interlayer insulating layer 155 may be formed on the upper etch stop layer 163. The second interlayer insulating layer 155 may be formed by forming an insulating material covering the upper etch stop layer 163 and performing a planarization process of exposing the upper surface of the dummy gate electrode 135. The upper etch stop layer 163 on the dummy gate electrode 135 may be removed through the planarization process to expose the upper surface of the dummy gate electrode 135. When the mask pattern layer 136 remains on the dummy gate electrode 135, the mask pattern layer 136 may be removed in the planarization process.

The dummy gate insulating layer 132 and the dummy gate electrode 135 may be removed through an exposed upper surface of the dummy gate electrode 135. The dummy gate insulating layer 132 and the dummy gate electrode 135 are selectively removed with respect to the isolation layer 107 and the active fins 105 thereunder to form a first opening OP1 for exposing the isolation layer 107 and the active fins 105. The dummy gate insulating layer 132 and the dummy gate electrode 135 may be removed through at least one of a dry etching process and a wet etching process.

Referring to FIG. 21, a gate structure 140 may be formed by forming a gate insulating layer 142, first and second gate electrodes 145 and 147, and a gate capping layer 148 in the first opening OP1 (see FIG. 20). The gate insulating layer 142 may be substantially formed conformally along sidewalls and a lower surface of the first opening OP1. The gate insulating layer 142 may include an oxide, a nitride, or a high-k dielectric material. The first and second gate electrodes 145 and 147 may include a metal or semiconductor material. Upper portions of the gate insulating layer 142 and the first and second gate electrodes 145 and 147 may be recessed, and the gate capping layer 148 may be formed to fill the recessed regions. The gate capping layer 148 may be formed, and a planarization process may be performed.

Referring to FIGS. 22 and 23, a second opening OP2 may be formed by patterning the second interlayer insulating layer 155. The second opening OP2 may be formed in a region in which the contact plug 180 (see FIGS. 1, 2, 5, and 9) is to be formed by removing a portion of the second interlayer insulating layer 155 through a separate mask layer 157 such as a photoresist pattern. An upper surface of the upper etch stop layer 163 may be exposed through the second opening OP2.

Referring to FIG. 24, the upper surface of the first interlayer insulating layer 153 may be exposed by removing the upper etch stop layer 163 exposed through the second opening OP2. An upper surface of the protective layer 151 may be exposed by removing the lower etch stop layer 161 together with the upper etch stop layer 163. The first interlayer insulating layer 153 and the protective layer 151 may be recessed in a process of etching the upper etch stop layer 163 and the lower etch stop layer 161. The upper etch stop layer 163 and the lower etch stop layer 161 may be removed and the exposed protective layer 151 may be removed, such that an upper surface of the source/drain regions 110 may be exposed through the second opening OP2. A portion of the first interlayer insulating layer 153 and portions of the source/drain region 110 may be recessed together in a process of etching the protective layer 151. Referring to FIGS. 24 and 10, the contact plug 180 may be formed by sequentially forming the silicide layer 181, the barrier layer 182, and the conductive layer 184 in the second opening OP2.

FIGS. 25 to 29 are views illustrating a method of manufacturing a semiconductor device according to some embodiments of the inventive concept. FIGS. 25 to 29 may be processes performed after the processes of FIGS. 11 to 15.

Referring to FIG. 25, a protective layer 151 may be formed to cover an isolation layer 107, source/drain regions 110, and a dummy gate structure 130. A first interlayer insulating layer 153 may be formed on the protective layer 151. The first interlayer insulating layer 153 may be formed by forming an insulating material layer covering the protective layer 151 and performing a planarization process of exposing an upper surface of the dummy gate electrode 135. The protective layer 151 on a dummy gate electrode 135 may be removed through the planarization process to expose an upper surface of the dummy gate electrode 135. The first interlayer insulating layer 153 may be partially removed such that an upper surface thereof has a level which matches or is lower than an upper end MT of a merged growth portion ME of the source/drain regions 110 and is higher than a corner E of the source/drain regions 110.

Referring to FIG. 26, an etch stop layer 160 may be formed to cover the upper surface of the first interlayer insulating layer 153, an exposed upper surface of the protective layer 151, and exposed side surfaces of the dummy gate structure 130. The etch stop layer 160 may be formed by forming an insulating material layer and performing a planarization process of exposing the upper surface of the dummy gate electrode 135.

Referring to FIG. 27, a first opening OP1 may be formed by removing the dummy gate electrode 135 and a dummy gate insulating layer 132 through the exposed upper surface of the exposed dummy gate electrode 135.

Referring to FIG. 28, a gate structure 140 may be formed by forming a gate insulating layer 142, first and second gate electrodes 145 and 147, and a gate capping layer 148 in the first opening OP1 (see FIG. 27).

Referring to FIGS. 29 and 30, a second opening OP2 may be formed by patterning a second interlayer insulating layer 155. The second opening OP2 may be formed in a region in which the contact plug 180 (see FIGS. 1, 2, 5, and 9) is to be formed by removing a portion of the second interlayer insulating layer 155 through a separate mask layer 157 such as a photoresist pattern. An upper surface of the etch stop layer 160 may be exposed through the second opening OP2. The etch stop layer 160 having an exposed upper surface may be removed, and the upper surface of the first interlayer insulating layer 153 and the upper surface of the protective layer 151 may be exposed. The protective layer 151 may be removed, and surfaces of the source/drain regions 110 may be partially exposed. A silicide layer 181 may be formed on the exposed surfaces of the exposed source/drain regions 110.

Referring again to FIG. 6B, a contact plug 180 may be formed by sequentially forming a barrier layer 182 and a conductive layer 184 in the second opening OP2 (see FIG. 30).

According to some embodiments of the inventive concept, an etch stop layer can be provided to prevent an interlayer insulating layer from being excessively recessed in a process of forming a contact plug. The etch stop layer can function to adjust a depth of a contact hole in which the contact plug is disposed to minimize parasitic capacitance generated between the contact plug and a gate electrode.

While the embodiments of the inventive concept have been described with reference to the accompanying drawings, it should be understood by those skilled in the art that various modifications may be made without departing from the scope of the inventive concept and without changing essential features thereof. Therefore, the above-described embodiments should be considered in a descriptive sense only and not for purposes of limitation. 

What is claimed is:
 1. A semiconductor device comprising: active fins extending in a first direction on a substrate; an isolation layer on sides of the active fins; a gate structure formed to cross the active fins and the isolation layer and extending in a second direction that is perpendicular to the first direction; source/drain regions on the active fins on sidewalls of the gate structure; a first interlayer insulating layer on the isolation layer and formed in contact with a first portion of the sidewall of the gate structure and a first surface of the source/drain regions; an etch stop layer on the first interlayer insulating layer, a second portion of the sidewall of the gate structure, and a second surface of the source/drain regions; and contact plugs formed to pass through the etch stop layer and contacting the source/drain regions, wherein the source/drain regions have main growth portions in contact with upper surfaces of the active fins and merged growth portions in which edges of the main growth portions are merged into each other.
 2. The semiconductor device of claim 1, wherein the source/drain regions comprise a lateral protrusion protruding in an outward direction of the active fins and comprising a lateral protrusion end, and wherein a flat lower surface of the etch stop layer is at a first level which is higher than that of the lateral protrusion end relative to the substrate and is lower than that of an upper end of the merged growth portions.
 3. The semiconductor device of claim 2, wherein the flat lower surface of the etch stop layer is at a second level which matches or is higher than a midpoint between a level of the lateral protrusion end relative to the substrate and a third level of the upper end of the merged growth portions.
 4. The semiconductor device of claim 1, further comprising a protective layer on the isolation layer, the sidewalls of the gate structure, and the source/drain regions, wherein the protective layer is between the isolation layer and the first interlayer insulating layer, between the first interlayer insulating layer and the source/drain regions, between the source/drain regions and the etch stop layer, and between the etch stop layer and the gate structure.
 5. The semiconductor device of claim 1, further comprising: a lower etch stop layer covering the isolation layer, the source/drain regions, and the sidewalls of the gate structure, wherein the lower etch stop layer is between the isolation layer and the first interlayer insulating layer, between the first interlayer insulating layer and the source/drain regions, between the source/drain regions and the etch stop layer, and between the etch stop layer and the gate structure.
 6. The semiconductor device of claim 1, wherein a center line of one of the contact plugs is misaligned with a center line of a respective source/drain region of the source/drain regions in the second direction.
 7. The semiconductor device of claim 6, wherein a first end of the one of the contact plugs extends outward from a first end of the respective source/drain region, wherein a second end of the one of the contact plugs is on the respective source/drain region, and wherein a lower surface of an extended portion of the one of the contact plugs contacts the first interlayer insulating layer.
 8. The semiconductor device of claim 1, wherein one of the contact plugs comprises a silicide layer in contact with an upper surface of a respective source/drain region of the source/drain regions.
 9. A semiconductor device comprising: active fins extending in a first direction on a substrate; isolation layers on both sides of the active fins; a gate structure formed to cross the active fins and the isolation layers and extending in a second direction that is perpendicular to the first direction; source/drain regions on the active fins on sides of the gate structure; etch stop layers on sidewalls of the gate structure and the source/drain regions and having a sigma (Σ) shape; a first interlayer insulating layer interposed between the etch stop layers; and contact plugs formed to pass through the etch stop layers and contacting the source/drain regions.
 10. The semiconductor device of claim 9, wherein the etch stop layers comprise a lower etch stop layer on the isolation layers, the sidewalls of the gate structure, and the source/drain regions, and an upper etch stop layer on the lower etch stop layer and the first interlayer insulating layer.
 11. The semiconductor device of claim 10, wherein the lower etch stop layer comprises a lower upper surface in contact with a lower surface of the first interlayer insulating layer, a first side surface extending from a lower end of the source/drain regions in an outward and an upward direction of the source/drain regions, and a second side surface extending from an upper end of the first side surface in an inward and the upward direction of the source/drain regions, and wherein a first corner is between the lower upper surface and the first side surface, and a second corner is between the first side surface and the second side surface.
 12. The semiconductor device of claim 11, wherein a lower surface of the upper etch stop layer is at a level which is higher than that of the second corner and is lower than that of an upper end of a merged growth portion of the source/drain regions relative to the substrate.
 13. The semiconductor device of claim 11, wherein the upper etch stop layer has a flat lower surface in contact with an upper surface of the first interlayer insulating layer, wherein a third corner is between the flat lower surface and the second side surface, and a portion of the upper etch stop layer at a higher level than the third corner relative to the substrate is thicker than a portion thereof disposed at a lower level than the third corner relative to the substrate.
 14. The semiconductor device of claim 11, wherein a third corner is between the second side surface and a flat lower surface of the upper etch stop layer, and wherein the sigma (Σ) shape of the etch stop layers is formed by connecting the lower upper surface of the lower etch stop layer, the first corner, the first side surface, the second corner, the second side surface, the third corner, and the flat lower surface of the upper etch stop layer.
 15. The semiconductor device of claim 9, wherein a center line of a first one of the contact plugs is misaligned with a center line of a respective source/drain region of the source/drain regions in the second direction.
 16. The semiconductor device of claim 9, further comprising: a protective layer on the isolation layers, the sidewalls of the gate structure, and the source/drain regions, wherein the protective layer is in contact with a lower surface of a lower etch stop layer of the etch stop layers.
 17. A semiconductor device comprising: active fins extending in a first direction on a substrate; isolation layers disposed on sides of the active fins; a gate structure formed to cross the active fins and the isolation layers and extending in a second direction that is perpendicular to the first direction; source/drain regions on the active fins on sidewalls of the gate structure; a lower etch stop layer on the isolation layers, the source/drain regions, and the sidewalls of the gate structure; a first interlayer insulating layer on the lower etch stop layer and having a height less than that of an upper end of the source/drain regions; an upper etch stop layer on a portion of the lower etch stop layer and the first interlayer insulating layer; and contact plugs formed to pass through the lower etch stop layer and the upper etch stop layer to be in contact with an upper surface of the source/drain regions, wherein a center line of a first one of the contact plugs is misaligned with a center line of the source/drain region in the second direction.
 18. The semiconductor device of claim 17, wherein the source/drain regions comprise a lateral protrusion protruding in an outward direction of the active fins and comprising a lateral protrusion end, and wherein a lower surface of the upper etch stop layer is at a level which is higher than that of the lateral protrusion end relative to the substrate.
 19. The semiconductor device of claim 18, wherein the lower etch stop layer has a first side surface at a lower level and a second side surface disposed at a higher level with respect to the lateral protrusion end of the source/drain regions, wherein the first side surface extends from a lower end of the source/drain regions in an outward and an upward direction of the source/drain regions, and wherein the second side surface extends from an upper end of the first side surface in an inward and the upward direction of the source/drain regions.
 20. The semiconductor device of claim 17, wherein the source/drain regions comprise main growth portions in contact with upper surfaces of the active fins and merged growth portions in which edges of the main growth portions are merged into each other, and a lower surface of the upper etch stop layer is at a lower level than an upper end of a merged growth end of the source/drain regions relative to the substrate. 